170 POULTRY BREEDING 
of fertile eggs in spring as other hens in the flock, but 
while these eggs were fertile they lacked what Prof. Rice 
calls “hatchability,” that is, they would not hatch, the 
germs dying before the end of the period of incubation in 
a large percentage of them. This would indicate that it 
is best to discourage winter-laying in breeding stock. -If 
this were done systematically it would be impossible to 
select the best layers for breeders unless the pullets were 
tested the first year as layers and the best of them used 
the second year as breeders. 
FERTILITY OF EGGS.—Some experiments were 
made in Canada to determine how long eggs would re- 
main fertile after the male had been removed from his 
mates. Ten hens were separated from the male. The 
eggs laid each day were placed in an incubator and tested. 
Of the eggs laid the first four days after the male was 
taken away 70 per cent were fertile; of those laid the fifth 
day 60 per cent; the seventh 49 per cent; the eighth 12 
per cent; the ninth, 2 per cent; the tenth none. A test 
was made with 6 hens to determine how soon the eggs 
became fertile after the males were placed with them. 
On the third day 30 per cent were fertile; on the fourth, 
42 per cent; on the fifth, 50 per cent; on the sixth, 60 
per cent; on the seventh, 70 per cent; on the eighth, 68 
per cent; on the ninth, 70 per cent, and on the tenth, 74 
per cent. As rarely more than 75 per cent of the eggs 
produced under average conditions are fertile, this goes 
to show that mating a hen 10 days before the eggs are 
needed for hatching is sufficient. 
There is some reason to believe that the effect of mat- 
ing lasts longer than the figures indicate if hens are not 
laying at the time of copulation. In one case that came 
under our observation a pullet that had been running in 
